Lease obligation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2022	Sep. 30, 2021
Change in operating lease, right-of-use assets	$ (469)		$ (1,080)
Change in operating lease liabilities	(683)		(1,307)
Restricted cash included in deposits and other noncurrent assets	1,515		1,779
Lease expense	$ 900		$ 1,400
Weighted average remaining lease term	5 years 9 months 18 days
Weighted average incremental borrowing rate	7.40%
Total minimum lease payments
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current			Other Liabilities, Current
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent			Other Liabilities, Noncurrent
75 Sidney Street
Lease term					3 years 3 months 18 days
Change in operating lease, right-of-use assets		$ 14,500
Change in operating lease liabilities		17,000
Gain on termination of lease		$ 2,500
Restricted cash included in deposits and other noncurrent assets	$ 1,500